About the series: With a sour economy and an increasingly anxious American public, the workings of Washington are inextricably linked to electoral politics headed into this year’s midterms. NBC’s Ken Strickland sat down with nine lawmakers who will depart from the Senate after this year. Together, they represent 158 years of Senate service and offer unique insights into how the Senate works and how it has changed. Read more about the series
here.

The U.S. Senate’s polarizing debate and passage of three monumental bills over the past two years have led most Americans to believe that Republicans and Democrats simply cannot — or will not — work together. The economic stimulus, health care, and financial reform bills — trillions of dollars worth of legislation that touched every citizen — were all essentially party-line votes.

An examination of senators’ voting practices last year inspired this headline from a Congressional Quarterly analysis: "2009 Was The Most Partisan Year Ever."

But ask the men and women who have actually served in the chamber, and you’ll hear a less rancorous tune.

Almost all of the senators who are retiring or were defeated in their primary elections this year say that it’s hardly the most partisan of times. One goes so far as to call such a notion “absurd.” History is replete, they say, with more intense periods of animosity, more anger, and violence.

These departing veteran senators say that partisanship isn’t solely measured by vote totals in Congress' upper chamber, but by a bitterness that floods Washington as a whole and often soaks the entire nation.

“It’s possible that this is a very partisan time, and yet it’s not the most partisan time,” said Democratic Sen. Evan Bayh. The son of former Indiana Sen. Birch Bayh, who was elected in 1962, recalled the Civil Rights and Vietnam eras as more destructive than today’s political squabbles.

“I remember seeing machine gun nests on top of government buildings here in Washington to protect them from demonstrators,” he said of the 1960s. “We had political assassinations — Martin Luther King, Robert Kennedy. We had the anti-war demonstrators shot at Kent State University.”

Republican Sen. Robert Bennett, 77, agreed. “I’m old enough to remember Vietnam,” he said. “I'm old enough to remember the bitterness.”

For other senators, Congress' most caustic days were more recent. Sen. Judd Gregg, R-N.H., remembered the beginning of the “Reagan Revolution” as a time when “the intensity was much higher, much more visceral than what we have now.”

At the beginning of 1981, Ronald Reagan had just walloped Jimmy Carter in a landslide election, and Republicans had regained control of the Senate after 25 years of Democratic rule. But the House was still controlled by Democrats and their speaker of the House, Tip O’Neill.

“Tip O’Neill would just try to beat our brains out,” said Gregg, who had just arrived on the Hill as a freshman congressman that year. “He backed up a truck of manure every morning to your office door and unloaded it … and he was surrounded by people who took no prisoners.”

It’s all about the numbers
Some blame the perception of partisanship in the current Senate on the body’s party breakdown.

“It’s always been partisan,” said Sen. Jim Bunning, R-Ky. “But the reason it’s so partisan now is because of the big, wide separation in numbers.”

Since the beginning of the Obama administration, Senate Democrats have held either 60 or 59 votes — the first time a party has achieved such power in over three decades. Those filibuster-proof (or near filibuster-proof) majorities render Republicans virtually powerless to stop any united Democratic agenda. With a supermajority, the need for compromise is almost obsolete.

“So, what else is there to do except to try to stop [legislation],” Bunning said. “We can’t have any input on a bill.”

Despite its ebbs and flows, partisanship in the Senate is as old as the Constitution that created it. And it sometimes manifests itself in forms that don’t leap out at the first glance at charts that detail party-line votes.

When Ritchie first came to the Senate in 1976, each party was divided internally with conservative and liberal wings within both parties. Liberal Republicans voted with liberal Democrats, and conservative Democrats allied with like-minded lawmakers from across the aisle.

And while the result was usually the bipartisan passage of bills, the dynamic also created fierce partisan battles between the two groups.

The rift between liberals and conservatives over the Vietnam War, Bennett said, “was every bit as acid and toxic as the bitterness you have now.”

The Utah senator remembers sitting in the office of a House Democrat from Texas — Bennett was working as a lobbyist at the time — when the Texan received a phone call inviting him to an event at the White House with President Lyndon Johnson, also a Democrat from the Lone Star State.

“Tell him no,” the congressman barked to his staff. Bitterly at odds with a president of his own party and even his own state, this lawmaker refused even to take the phone call himself.

After the war limped to an end, public distaste over the Watergate scandal flushed in successive waves of Democrats, then Republicans. Conservative Southern Democrats were replaced by Republicans. Beginning in the 1980s, historian Ritchie said, the political parties grew more cohesive, erasing most intraparty fault lines and creating the classic two-party matchups of today.

He cited the founding fathers’ debates in Philadelphia that created the country and formed its government, saying it was hardly a sedate and cordial summit. “There was a real clash of ideals … it was raucous, rollicking, tough. It was as partisan as anything, in fact, more so in some ways.”

Dodd said he’s “mystified” by arguments that senators should become more bipartisan. “It’s the wrong words,” he contended, “we need better civility in the process.”

Most popular

With 30 years experience in the Senate, Dodd worries that there has been an increase in deeply personal attacks, with members seeking to destroy reputations or link an opponent to a polarizing group. Such behavior, Dodd claims, prevents senators from working together.

“If I attack you personally, there’s no way in the world you're going to sit down with me and find that common ground,” Dodd said. “That just defies human nature.”

Msnbc.com's Carrie Dann contributed to this story

Coming on Tuesday: The complex web of Senate rules allows for more productivity than most Americans understand, and it also grants dramatic amounts of power to single dissenters. And you’ll be surprised to hear what some senators have to say about them.

Video: Outgoing senators give exit interviews to NBC News

>>>there's a broad consensus among voters that the
111th congress
is too partisan to get anything worthwhile done, but ask the veteran senators leaving and you'll get a different story.

>>ken stricklin conducting exit interviews with nine of the outgoing senators. ken is here with us with some of these interviews. i'm sure when the cameras are off and they don't have to worry about re-election, a will the of these senators could open up. what surprised you most?

>>first of all, consider the wide range of people leaving. you have like
chris dodd
, who's been there for 30 years.
bob bennett
, who was voted out by his own party.
kit bond
.
judd gregg
. a lot of republicans are going to tell you they are just heartbroken about this guy leaving. and for them to sit down without the camera, which completely changes the dynamic, and talk about topics, partisanship, regrets, gave a view that really bucks the view of the way washington works. the first question was about partisanship.

>>what's interesting, last week, you were saying that on the issue of the partisanship, there was one change that all of the senators cited. one big change that happened with the gallery. both in actuality and sort of virtually.

>>we're going to do a four-part series and tomorrow, we talk about this as well. it's what
byron dorgan
referred to as the bleacher section. 24-hour cable, blogs, the surge of outside
interest groups
. that basically conflicts with compromise. the senate, the way the rules are set up, it forces people to compromise. but these outside groups see any type of compromise or caving as disloyalty and there start the protests.

>>we saw that this weekend when boehner said he might be open to voting for
middle class
tax cuts. we talk about this issue of partisanship, the conventional wisdom seems to be that the current congress has the most visit rollic than ever. one interview with senator bayh -- clearly saying as bad as it feels now, you've got to have a sense of history.

>>these interviews provides context. something we don't always get.
judd gregg
, he talked about
1980
when he was a republican in the democratic house when reagan had come in. he told this great story that -- would take a truckload of manure and dump it every day. to get a better perspective, i talked to a senate historian, don richy. he had to remind me of something important, which is that in the '60s and '70s, the two parties were split internally. republicans had a liberal wing and democrats had a significant conservative wing, but the voters,
over time
, changed that.

>>so, it actually brings up this point, the idea that in the good old days, there was compromise. that's just simply because the voters hadn't caught up with the national identities of both parties and so now, the reason you don't have this is because
conservative democrats
came from the
southern states
and the
liberal republicans
come from states,
blue states
in the northeast, which now all elect mostly democrats.

>>another idea
chris dodd
mentioned, he said
partisan politics
is what made the place. he said what we need is more comity. not to be confused with comedy. just more cooperation between the two parties. he said you go back to
1776
, when they formed this country, they were at each other's throats.

>>and this other thing people say a lot is that a
jet travel
, which is really minimized the civility of the chamber because now members who might spend more time in washington and end up socializing with other members, they go home on the weekends. might be good for democracy, might be good for their interactions with voter, but perhaps not for their own relationships.

>>even at the
end of the day
, when the rules get in the way, when the bleacher section roars too loud, it's really the personal relationships across the aisle. i think on wednesday we'll tell a story about kennedy and
phil graham
.

>>interesting. ken stricklin with an eye opening
exit interview
. something we wish we could have gotten on camera. thanks very much. read more of ken's exclusive exit interviews, politics.msnbc.com, including full transcripts of the interviews.